Fred Hellerman, a singer, guitarist and songwriter and the last surviving member of the Weavers, the quartet that in the 1950s helped usher in the folk music revival, died on Thursday at his home in Weston, Conn. He was 89... With songs like “If I Had a Hammer,” “Goodnight Irene” and “Kisses Sweeter Than Wine,” the Weavers brought folk music to a mass audience, paving the way for singers like Joan Baez, Bob Dylan and Peter, Paul and Mary, who galvanized a young, politically conscious audience in the 1960s. Mr. Hellerman’s mellow baritone, rock-steady guitar and songwriting talent made him...